Process of drying leather and similarly tautly stretched units



Feb. 22, 1938. A. o. HURXTHAL I I I 2,109,425

PROCESS OF DRYING LEATHER AND SIMILARLY TAUTLY STRETCHED UNITS FiledJan. 29, 1936 3 Shets-Sheet 1 OOOJUQOOODOLOO c o '2 on 000000 000000000' 70 0 oo'o or out" ODOOQUO Feb. 22, 1938. A. o. HURXTHAL PROCESS OFDRYING LEATHER AND SIMILARLY TAUTLY STRETCHED UNITS Filed Jan. 29 1936 3Shets-Sheet 2 m a Q frz vezzz or Feb. 22, 1938. A. 0. HURXTHAL PROCESSOF DRYING LEATHER AND SIMILARLY TAUTLY STRETCHED UNITS Filed Jan, 29,1936 3 Sheets-Sheet 3 Patented Feb. 22, 1938 PROCESS OF DRYING LEATHERAND SIMI- LARLY TAUTLY 'STRETCHED UNITS Alpheu's o. Hurxthal,Philadelphia, Pa., assignmto Proctor & Schwartz, Incorporated,Philadelphia, Pa., a corporation of Pennsylvania Application January 29,1936, Serial No. 61,392

1 Claim.

This invention relates to a new and improved method of drying animalhides, leather or corresponding units of other materials, particularlythose of irregular sizes and contours, which are 5 normally stretched onframes or boards individual to the units and wherein the units aresecured to the drying and-stretching frames by toggles or other deviceswhich grip each unit at spaced intervals around its edge.

I In the case of leather, 1. e. pretanned animal hides of differentkinds; it is customary to stretch..- each unit on a frame comprising awire mesh screen or perforated sheet capable of receiving the hooks ofthe toggles which are clamped to the edges of the unit to draw, stretchand hold the unit tightly and evenly over and throughout its entirearea.

The loaded frames are usually inserted into a drier in relatively closelaterally'spaced parallel relation to each other. Drying is effected byair blowing from one side or end of the drying chamber across andbetween the plurality of frames, with the air moving in the direction ofthe plane of each frame and across the unit carried thereby from oneedge thereof toward the other edge thereof.

Under the above noted process, or system, that edge of the unit nearestthe source of the drying air, and with which the air contacts first,begins travels. Consequently, that edge of the unit which lies furthestaway from the source of the drying air dries last and before this edgeis completely dry the opposite edge, that is, the edge nearest thesource of drying air has become overdried, resulting in that edge andthe adjacent portion of the unit becoming harsh while the last driedportion, which is dried to the proper extent, is relatively soft andpliable.

The progressive drying of the unit from one side toward the oppositeside thereof, in addition to the above, is responsible for detrimentalstrains being set up in the unit itself. unit dries it shrinks and wherethe drying is progressive from one side to the other the shrinkinglikewise follows from one side to the other, thus creating undesirablestrains, under which the unit is placed by such uneven shrinkage, andwhich frequently causes the leather to pull loose from the toggles witha resultant damage to the leather at and adjacent the edges of the unit.3

The object of the present invention is to As the REISSUED,

cause the drying air to impinge upon all parts of the unitsimultaneously, in a direction substantially perpendicular to the planeof the unit, whereby even and uniform drying and shrinking of .the unitis accomplished-at all points 'through- 5 out-its entire area at thesame time.

Under the method forming the subject matter of the present invention theunit dries in approximately one-third the time required for drying thesame units under the old method above described. I

In the drying of leather and similar-units, one

of they greatest handicaps of the industry has been the expense involvedin the provision of sufficient numbers of frames and toggles. Under themethod forming the subject of the present invention, and wherein thedrying time is reduced to substantially one-third of the drying timerequired under the old method, it'naturally follows that eachframe andits complement of toggles is available for use three times as often asunder the old method. Consequently, only onethird of the number offrames and toggles will be required for drying a predetermined number ofunits or three times as many units may be dried in the same time andwith the same equipment as was formerly required for the drying of thelesser number of units.

Under'the old system in order to lessen the unequal, drying of the unitsand the detrimental effects thereof it was necessary to employ some formof humidifying apparatus in the drier for retaining or supplyingmoisture to the air in circulation. This condition lengthened the timenecessary to dry the units, whereas under the system or process formingthe subject of the present invention." it is possible to extract themoisture from the air in circulation and to impinge the dry air againstthe units, thus materially reducing the time necessary for the drying ofeach unit and at the same time eliminating the detrimental effects ofthe. strains normally set up by the unequal drying and shrinking underthe old method.

The drying of leather or other units in accordance with the principlesof the present invention may be readily carried on in an apparatus suchas that disclosed .in the accompanying drawings, of which:

Fig. 1 is a vertical longitudinal section of the drier;

Fig. 2 is a sectional plan view taken on the line 2-2, Fig. 1; and

Fig. 3 is a vertical transverse section taken on the line 3-3. s-

'As shown in the drawings, the apparatus comprises an outer casing lenclosing an air conditioning chamber 2 at one end, adrying chamber 1 atthe opposite end, a circulating chamber 4 above the chambers 2 and 3 andextending longitudinally of the drier and a lower circulating chamber 8extending longitudinally of the casing beneath the chambers 2 and 8.

The circulating chambers .4 and 8 communicate at one end with the airconditioning chamber 2, through heating or cooling units 8 and L 7vertical partitions I! which are of a foraminous nature throughout andwhich divide the chamber into frame receiving compartments l8, I8, inwhich the units of material to be dried are placed, and intermediatechannels I! which communicate at one end with an air space I 8 formed atthe one end of the drying chamber 3. The interiors of the compartmentsl8 communicate at their tops and bottoms respectively with the upper andlower circulating chambers 4 and 5. The vertical partitions I! asillustrated in the drawings are provided with perforations i8 over theirentire areas.

The leather or other units a: are stretched tautly on suitable dryingframes which each include in the present instance a perforated plate 20having openings 28a over its entire surface for receiving the hooks ofthe toggles (not shown) which, as is well known in the art, grip theleather or other unit at desired points around the edges of the unit andsupport the unit in laterally spaced substantially parallel relation tothe perforated plate 20.

Each plate 20 is hung within a frame 2| by suitable straps 22, and eachframe 2| in turn is pivoted at its opposite sides, as illustrated at 23,23, within a supporting frame 24. Each supporting frame 24 is providedwith wheels 25 arranged to run on overhead tracks 28 mounted in theupper chamber 4 of the casing I.

Each of the frames 2| is provided with an endplate 21, said end platescombining-with vertical plates 28, 28 at the receiving end of the drierto form an end wall on the drier when the drying frames are in positionwithin the drier.

As shown in Fig. 2, the partitions l8, II are spaced apart adjacent theair space l8 to form the mouths of the channels I! and converge towardthe opposite end of the drier to progressively reduce the width of eachchannel ll. At the last said end of the drier each converging pair ofpartitions II are joined together and to one of the end plates 28.

With the fan I in operation, the air is moved or drawn out of the endcompartment 2 and propelled into the air space II, at the one end of thechamber 3, and moves longitudinally of,

the drier from the air space l8 into the wide ends of the channels II.The converging relation of the perforated partitions l8 traps theiongitudinally flowing air and causes it to move out of the channels I!substantially at right angles thereto and'perpendicular to thepartitions ll, entering the compartments i8 from opposite sides thereofand impinging upon the exposed surface of the unit 1 carried by each ofthe plates 28 within each compartment l8.

In some instances, there may be a unit a.

mounted on each side of each plate 28. However, whether there is a uniton but one side or, a uniton each side of each plate, the air passingfrom the channels I! into the compartment i8 will impinge upon the oneor both units a: at all points over the entire area thereof andsubstantially at right angles to the plane thereof, whereby uniformdrying at all points throughout the area of each unit occurssimultaneously.

vention to use a smaller number of larger holes distributed over thearea of the unit or a single large hole at the center of the surface ofthe unit toproject the air against the .unit substantially at the centerthereof or at'a number of points about the center of the unit to causethe air to move from the jet or Jets in contact with the surface of theunit toward the marginal edges thereof and whereby a uniform drying ofthe unit may be accomplished. However, the large number of small Jets ispreferable.

I claim:

The method of drying wet tanned hides prior to staking or otherfinishing treatment of the surface of the hide. which consists instretching a hide in all directions outwardly from the central areathereof toward the marginal edges of the hide, securing the edges of thestretched hide to a suitable support to resist subsequent shrinkage ofthe hide, and impinging Jets of drying air against the surface of thehide at relatively closely spaced points simultaneously oversubstantially the entire area of said surface to effect uniform dryingof the hide at substantially all points over the entire area of saidsurface simultane-

